DCA Project Planning & Execution 5

Question 1

A project requires containers to be automatically restarted if they crash, but not if stopped manually. Which restart policy should be configured?

Accepted Answer

--restart=unless-stopped

Answer

The 'unless-stopped' policy restarts crashed containers automatically but respects an explicit manual stop, unlike 'always'.

Question 2

During project planning, the security team requires all containers to run as a non-root user. How is this enforced in a Dockerfile?

Accepted Answer

USER <username_or_uid> instruction before the CMD or ENTRYPOINT

Answer

The USER instruction in a Dockerfile sets the default user for subsequent RUN, CMD, and ENTRYPOINT instructions in the container.

Question 3

A team plans to use Docker configs (not secrets) to distribute non-sensitive configuration to Swarm services. What is a key difference between Docker configs and Docker secrets?

Accepted Answer

Configs are mounted at arbitrary paths; secrets are always mounted at /run/secrets/

Answer

Secrets are always mounted under /run/secrets/<secret_name>, while configs can be mounted at any path specified in the service definition.

Question 4

When planning the execution environment, a developer wants to override the default command of a Docker image at runtime without modifying the Dockerfile. Which approach is correct?

Accepted Answer

docker run myimage <new_command> appends to ENTRYPOINT and replaces CMD

Answer

Arguments passed after the image name in 'docker run' replace the default CMD; use --entrypoint to override ENTRYPOINT instead.

Question 5

A project execution plan requires rolling back a Docker Swarm service to its previous configuration after a failed update. What is the correct command?

Accepted Answer

docker service update --rollback <service_name>

Answer

The 'docker service update --rollback' command reverts a service to the configuration it had before the last 'docker service update'.

DCA - Docker Certified Associate Exam Practice Test

DCA - Docker Certified Associate Exam Practice Test

DCA Project Planning & Execution 5